Solvay: AgRHO^® S-Boost IFA — A New Ally for Biologicals Efficacy

A new mindset is bustling in farming: instead of placing biological inputs on the seed, why not apply them in the seed furrow where they can be accessed by the seed to get a good start? This mode of application, called in-furrow, can be used to add different inputs in the crop, including biologicals, and is a growing trend, especially for soybeans in Brazil.

The use of bio-inputs in soybean crops has become increasingly important for achieving higher productivity, cost reduction, and greater sustainability. Inoculation and co-inoculation with selected strains of Bradyrhizobium japonicum and Azospirillum brasilense, for example, can considerably improve the yield of this crop. Additionally, several biological nematicides, such as Paecilomyces lilacinus and other fungi, can be employed to protect the roots from nematode infection.

However, applying bio-inputs on seed brings a major obstacle: potential incompatibility between the microorganisms and the standard seed treatments. This is why the development of alternative solutions to improve the viability of microorganisms is urgently needed.

The AgRHO^® S-Boost IFA was designed to address this unmet need in agriculture, enhancing the performance of biologicals in the field. This is achieved by the utilization of a chemically modified biobased macromolecule extracted from the leguminous plant Cyamopsis tetragonoloba, also known as guar.

When applied in-furrow, this macromolecule physically modifies the soil by acting as an attractor of water and nutrients. It thus modifies the environment and boosts the plant's metabolism by strengthening the development of its roots, in particular the secondary ones. Figure 1 shows the effect of AgRHO^® S-Boost IFA in the soil.

Figure 1.  The effect of AgRHO^® S-Boost IFA on soil shown through changes in soil capillarity and soil structure

The health of the soil, which is a living ecosystem, depends on intricate interactions between its biotic (linked to living beings) and abiotic components. Among these interactions, symbiosis between microorganisms plays an important role in determining soil health and, consequently, crop yields. This is why it is important to understand the interactions of AgRHO^® S-Boost IFA with inoculants and bionematicides. To achieve this, greenhouse and field trials were carried out.

Positive synergistic effect of AgRHO^® S-Boost IFA and biologicals on crops

Based on good biological compatibility results obtained by initial tests performed in-vitro, the nodulation effect on soybean was evaluated with different doses of the AgRHO^® S-Boost IFA applied in-furrow in greenhouse trials. Statistically significant differences in nodule weight were observed among the treatments.

At 30 days after application (DAA), the plants treated with 0.2L/ha of AgRHO^® S-Boost IFA (T2) showed the highest average nodule weight (0.25 g), a significant improvement in comparison to the reference (T1). Furthermore, soybean treated with AgRHO^® S-Boost IFA at 1.0 L/ha (T4) showed higher nodule weight at 45 and 60 DAA, an improvement of 160 and 59% in comparison with the reference (T1), respectively.

Figure 2.  Positive synergistic effect of in-furrow application of AgRHO^® S-Boost IFA and biological inoculant on total nodule weight of soybean. Greenhouse trials.  
T1 – biological inoculant alone;
T2 – biological inoculant + 0.2L/ha of AgRHO^® S-Boost IFA;
T3 – biological inoculant + 0.5L/ha of AgRHO^® S-Boost IFA;
T4 – biological inoculant + 1.0L/ha of AgRHO^® S-Boost IFA.

The infection of legume roots by Bradyrhizobium bacteria leads to the formation of specialized structures called root nodules, where nitrogen fixation can occur. This process involves the plant secreting flavonoids, which trigger the activation of specific bacterial genes responsible for nodulation. These genes are essential for the successful formation and functioning of the nodules.

The improved nodulation effect observed in Figure 2 can be attributed to alteration of the physico-chemical properties of the soil facilitated by AgRHO^® S-Boost IFA. This modification enables improved water and nutrient transportation to the seeds, while also promoting the growth of microorganisms in the soil. Another potential explanation could be related to the AgRHO^® S-Boost IFA molecular structure, which acts as a signal molecule (Nod factor) during the nodulation process.

Synergies between AgRHO^® S-Boost IFA at 0.5 and 1 L/ha and commercial bionematicides (Paecilomyces lilacinus, dose: 0.25 kg/ha) were also evaluated in greenhouse trials. Pratylenchus brachyurus control efficacy was calculated considering the difference between the final (60 days after application) and initial nematode populations. AgRHO^® S-Boost IFA at 0.5 L/ha improves nematode control by 67 % after 96 hours of mixture incubation, as shown in Figure 3.

Figure 3. Positive synergistic effect of in-furrow application of AgRHO^® S-Boost IFA and bionematicide on nematode control at 60 days after application. Greenhouse trials.
T1 – bionematicide alone;
T2 – bionematicide + 0.5L/ha of AgRHO^® S-Boost IFA;
T3 – bionematicide + 1.0L/ha of AgRHO^® S-Boost IFA.

AgRHO^Ⓡ S-Boost IFA leading to increased soybean yield

The performance of AgRHO^® S-Boost IFA at 0.5 L/ha on yield improvement of soybean was evaluated in field trials in different regions across Brazil. Results are shown in Figure 4. The Piano chart is a histogram representing the gain or loss of yield due to the applied modality compared to the reference. In this graphic, the yield difference compared to the reference modality is calculated and noted ∆yield, expressed in sac/ha. The histogram is sorted from largest values to smallest.

Figure 4.  Piano Chart showing the positive effect of AgRHO^® S-Boost IFA 0.5 L/ha on soybean yield. Trials performed in Brazil during the 2021 season.

AgRHO^® S-Boost IFA resulted in a significant soybean yield increase (+7% on average) compared with the control. Moreover, a yield increase was observed in all plots.

Conclusion

The association of AgRHO^® S-Boost IFA with biologicals presents a highly effective solution for enhancing the performance of microorganisms applied in-furrow, particularly bionematicides and inoculants. This association has been validated in the field, demonstrating a remarkable 7% increase in soybean yield.

Beyond solutions for in-furrow applications, Solvay has developed a full range of solutions for biologicals, accompanying the transition to more sustainable agriculture. Indeed, convinced that formulation makes the difference, Solvay is committed to support formulators in finding optimized strategies for improved biological efficacy. For additional information, please send your inquiry to our biologicals manager, fernanda.costa@solvay.com.

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